15. Male Circumcision: A New Defense Against HIV

Male circumcision cuts the risk of HIV transmission in men by about 60 percent and should be scaled up in countries hardest hit by the epidemic, the World Health Organization (WHO) announced in March, citing compelling evidence from three large trials in Kenya, Uganda, and South Africa.

Since the 1980s, dozens of smaller studies have suggested that countries with high rates of circumcision, like the Muslim nations of western Africa, have lower rates of AIDS, whereas southern* Africa, where circumcision is rare, has been ravaged by the epidemic. There, a 2006 study suggests, circumcision could prevent about 6 million HIV infections and 3 million deaths over 20 years. Still, the WHO held back its recommendation until 2007, citing the need for randomized clinical trials.

“Circumcision was ignored for ages,” says Daniel Halperin, an AIDS researcher at the Harvard School of Public Health, who laid out the case for circumcision in The Lancetas far back as 1999. “What I mainly criticize the WHO for is that, even with dozens and dozens of powerful studies, they refused to even talk about it.”

Circumcision is thought to prevent infection because the underside of the foreskin is rich in immune cells that are particularly vulnerable to HIV. Small tears in the foreskin during intercourse can also allow the virus to slip into the body.

Circumcision could reduce the odds of an infected man’s transmitting the virus to a female partner by 30 percent or more. For all its benefits, though, the WHO cautions that it should not replace standard methods of prevention like the use of condoms.